The present invention relates to catheters, and more particularly to balloon structures for such catheters.
In the past, a various assortment of catheters, such as Foley catheters and endotracheal tubes, have been proposed for use in patients. In the case of urinary catheters, a conventional Foley catheter is normally constructed having a shaft defining a drainage lumen extending from a drainage eye adjacent a distal end of the shaft and an inflation lumen in the wall of the shaft, and having an expansible balloon overlying a distal portion of the shaft and communicating with the inflation lumen. In use, the distal end of the catheter is passed through the urethra until the drainage eye and balloon are located in the patient's bladder, and the balloon is inflated in the bladder to retain the catheter in the patient with a proximal end of the catheter located outside the patient's body. During catheterization, urine passes from the bladder through the drainage eye and lumen, and from the catheter through a drainage tube to a bag for collection therein.
A great majority of Foley catheters have been made from latex rubber through dipping techniques known to the art. However, a number of problems have been encountered with conventional latex catheters, such as difficulties in manufacture and delamination of the catheter sidewalls causing blockage in the inflation lumen. Accordingly, there has been a desire to construct catheters from materials which display superior properties both from the view of improved performance during use and permitting simplified manufacture to reduce cost. For example, it is preferred that the catheter shaft be made from a material which can be extruded in order to facilitate the manufacturing process and eliminate the delamination problems associated with dipped latex catheters. Additionally, the materials of the catheter shaft must be compatible with the patient's body to prevent deleterious results during use. The shaft, although flexible, should also have sufficient rigidity to permit placement of the catheter and prevent collapse of the shaft side walls. The balloon, of course, should be flexible and elastic to permit inflation in the patient's bladder, and preferably has a sufficient memory to assume its initial deflated configuration against the catheter shaft while being removed from the patient. It is desirable that the balloon may be formed by extrusion or molding techniques.
Assuming that a compatible adhesive exists for possibly differing materials of the balloon and shaft, such adhesive may be utilized to bond opposed ends of the balloon to spaced zones of the shaft. Of course, it is necessary to apply sufficient adhesive in the zones to obtain a satisfactory bond and close a cavity intermediate the zones for proper inflation of the balloon during use. However, the fabrication of catheters in this manner poses a dilemma for the manufacturer. If an insufficient amount of adhesive is placed between the balloon and shaft, then a satisfactory bond may not be obtained. Alternatively, if too much adhesive is used during bonding of the balloon, then the adhesive may spread laterally when the balloon is pressed onto the shaft, thus limiting the effective region of the balloon which may be inflated during use. Further, due to uncertainty in the width of the bonding zones which may vary circumferentially around the shaft, such bonding techniques may result in non-uniform balloons which inflate into differing shapes and at different pressures during use.